1. Field of the Invention
The present invention relates to a heat exchanger having tubes through which fluid passes and corrugated fins.
2. Description of Related Art
Conventionally, tubes and fins are joined with each other by brazing material covering (clad) the surface of the tubes or fins.
However, the tubes or fins covered by the brazing material are high in manufacturing cost. Furthermore, if the fin is covered by the brazing material, the heat exchanging performance of the heat exchanger is reduced due to diffusion effect of the brazing material at the heating of the brazing process.
Further, if the thickness of the tubes and the fins is reduced to improve the heat exchanging performance, a problem may be noticeable that erosion occurs in the tube or fin due to the diffusion effect of the brazing material.
To solve these problems, it may be possible to spread brazing material, in form of paste, powder, solid or the like, only on contact portions of fin or tube. However, as the tube interval (the difference in size between the peak and the valley of the fin) increases by the thickness of the spread brazing material, it is difficult to, for example, insert and assemble the tubes into a header tank (core plate), thereby compromising the assembly of fins, tubes and the like and reliability of brazing between the fins and the tubes.
Further, according to the above method, the brazing material is rubbed and may be easily removed when the tubes and the fins are combined.